Enzyme. An organic catalyst (q.v.) that consists principally of proteins (q.v.) and is formed only by living tissue of either animal or plant origin. As a catalyst, it initiates, sustains, and regulates the rates of both hydrolyzing (q.v.) and synthesizing (q.v.) reactions without being chemically affected or becoming part of any of the reaction products. Enzyme categories of special significance in baking are carbohydrases (q.v.) which include the amylases (q.v.) that degrade starch (q.v.) into simpler carbohydrates (q.v.), proteinases (q.v.) that modify the proteins (q.v.) present in dough, and lipases (q.v.) that hydrolyze the fats (q.v.) of wheat and flour.